A Modern Utopia Requires an Entire Planet

No less than a planet will serve the purpose of a modern Utopia. Time was when a mountain valley or an island seemed to promise sufficient isolation for a polity to maintain itself intact from outward force; the Republic of Plato stood armed ready for defensive war, and the New Atlantis and the Utopia of More in theory, like China and Japan through many centuries of effectual practice, held themselves isolated from intruders. Such late instances as Butler's satirical %u201CErewhon,%u201D and Mr. Stead's queendom of inverted sexual conditions in Central Africa, found the Tibetan method of slaughtering the inquiring visitor a simple, sufficient rule. But the whole trend of modern thought is against the permanence of any such enclosures. We are acutely aware nowadays that, however subtly contrived a State may be, outside your boundary lines the epidemic, the breeding barbarian or the economic power, will gather its strength to overcome you.

H.G. Wells, A Modern Utopia (2004)